The present invention relates to a plug for the tap hole of a metallurgical vessel and particularly relates to a tap hole plug per se, as well as apparatus and methods for inserting the plug into the tap hole.
In metallurgical vessels, there is conventionally provided a tap hole through the side wall of the vessel and through which molten metal from the vessel may be poured when the vessel is pivoted about a horizontal axis. Tap holes are typically filled with a plug designed to seal the tap hole opening, notwithstanding contact between the tap hole plug and slag formed on top of the molten metal, and also to melt when in contact with the molten metal in order that the molten metal may be poured through the tap hole. In this manner, the slag remains in the vessel.
Generally, tap holes are subject to greater wear in use than the interior of the vessel lining. For example, the interior end of the tap hole tends to become conical in shape and the circularity of the tap hole often becomes irregular and distorted. In certain circumstances, tap holes have evolved through use into generally D-shaped openings with molten metal and slag depositing along the lower surfaces of the tap holes. That is to say, slag whiskers or occasional slag carry-over and molten metal stoppings often reduce the circular opening to a D shape. All of these irregularities render the tap holes difficult to plug using conventional tap hole plugs.
As will be appreciated, there are a substantial number of different types of tap hole plugs that have been proposed and constructed in the past.
However, none of these alleviate the problem of the irregular enlargement of the hole through use of afford plugs practical for use with non-circular openings. Furthermore, tap hole plugs are difficult to insert into the tap holes. For example, while tap holes are ordinarily of a diameter approximately 6 inches and a length on the order of about 4 feet, it is customary to stand back 10 to 15 feet from the tap hole and insert the plug. It is therefore very often difficult to guide the plug into the tap hole and secure it in place inasmuch as plug placement and securement are accomplished manually.
According to the present invention, there is provided a tap hole plug which is readily and easily inserted into the tap hole for sealing the hole adjacent the inner surface of the vessel.
Particularly, the plug comprises a canister containing refractory mortar, preferably zircon colloidal silica refractory mortar, disposed between a pair of end plates and about a central member extending between the end plates. The end plate nearer the outside of the vessel in which the plug is to be inserted is axially movable along the central member toward the opposite end plate to compress or apply a pressure to the refractory mortar disposed between the plates. The canister has a radially opening aperture which extends about the periphery of the canister. Consequently, upon compressing the mortar between the end plates, the mortar flows radially outwardly through the aperture to bear and seal against the walls defining the tap hole. Preferably, the canister is provided with a right angularly related V-shaped guide which projects from the forward end of the canister. This guide facilitates insertion of the plug into the tap hole from outside of the vessel by enabling the plug to be centered within the tap hole.
In order to insert the plug of the present invention into the tap hole, there is provided an applicator plunger. The plunger is formed of inner, outer and intermediate concentric sleeves. The inner and outer sleeves are secured one to the other against axial movement relative to one another by a pin which extends through diametrically opposed, longitudinally extending, slot formed in the intermediate sleeve. Thus, the intermediate sleeve is axially movable relative to both the inner and outer sleeves. The intermediate sleeve mounts a pusher head at one end, while the corresponding end of the inner sleeve is internally threaded for connection with a central member of the plug. The outer sleeve carries a laterally projecting stop for engagement with the outer wall of the vessel. The stop is located a predetermined distance from the pusher head determined by the thickness of the vessel wall, i.e., the length of the tap hole, and the desired location of the plug in the tap hole. The intermediate sleeve includes an encircling coil spring connecting it and the outer sleeve for biasing such sleeves for axial movement into a position where the pusher head and the connecting means lie substantially flush adjacent one end of the plunger.
When using the plunger, the central member of the plug is threaded to the end of the inner sleeve such that the plug may be carried with the plunger. Standing back 10 to 15 feet from the vessel and using an extension rod releasably secured to the rear end of the plunger, the operator then extends the plunger such that the guide on the plug enters the tap hole. The plug is sized to leave a small annular space between it and the walls defining the tap hole upon displacing the plug into the tap hole. Advancement of the plunger to insert the plug into the tap hole eventually causes the stop carried by the outer sleeve to butt against the outer surface of the vessel. When the plunger stops, the plug is properly located intermediate the ends of the tap hole short of the inner surface of the vessel. The intermediate sleeve carrying the pusher head is then advanced relative to the outer and inner sleeves. By advancing the pusher head against the movable end plate of the plug and advancing it toward the opposite end plate, the mortar between the end plates is compressed and forced radially outwardly to engage and seal against the walls of the tap hole. The heat of the furnace sets up the refractory mortar to seal the tap hole opening. It will thus be appreciated that the mortar is displaced radially outwardly similarly as an extrusion and fills the gap or annular space between the wall defining the tap hole and the plug. Consequently, the particular shape or irregularities in the sleeve of the tap hole is of little consequence in sealing the tap hole, provided the shape does not preclude entry of the plug into the tap hole. Once the plug has been located and sealed in the tap hole, the plunger is rotated to unthread the inner sleeve from the plug withdrawn from the tap hole.
In a preferred form of the present invention, zircon colloidal silica refractory mortar is used, although it will be appreciated that other types of mortar, including MgO, Al.sub.2 O.sub.3 and silica, may be used.
Thus, in accordance with a present preferred embodiment of the invention, there is provided a plug for the tap hole of a metallurgical vessel comprising a canister for reception within the tap hole, the canister having an axis. A refractory mortar is carried by the canister and disposed about the axis. Means are provided for retaining the mortar in the canister precluding its displacement in a radially outward direction. Means are additionally carried by the canister for displacing the refractory mortar within the canister generally radially outwardly thereof when the canister is disposed in the tap hole to seal against the walls of the vessel defining the tap hole. Preferably, the canister has a pair of axially spaced end plates wherein one of the end plates is movable toward the other end plate to displace the mortar in a radial direction. A guide is provided in the canister, including a central member on which the movable plate is guided toward its opposite end plate in response to the pushing action of the pusher head.
According to the present invention, there is also provided apparatus for inserting a plug in a tap hole of a metallurgical vessel comprising a plunger having a pair of concentric sleeves axially movable relative to one another, a pusher head disposed adjacent one end of one of the sleeves for engaging the plug, together with means carried by the other sleeve adjacent a like end thereof as the one sleeve end for connecting the other sleeve and the plug one to the other whereby the pusher head and the connecting means may be axially displaced relative to one another. Preferably, inner, outer and intermediate sleeves are provided with the pusher head and connecting means being formed on the intermediate and inner sleeves, respectively. In a preferred form hereof, a stop is carried by the outer sleeve at a location spaced from the pusher for engaging the wall of the metallurgical vessel upon insertion of the pusher into the tap hole whereby the extent of insertion into the tap hole of the pusher may be limited, thereby properly locating the plug in the tap hole.
In accordance with another aspect of the present invention, there is provided a method of inserting a plug in the tap hole of a metallurgical vessel comprising the steps of providing a plug containing a refractory mortar, providing a plunger having a pair of concentric sleeves axially movable relative to one another, one sleeve having a plug connecting means at a like end thereof as the one sleeve, connecting the plug and the other sleeve one to the other, inserting the plug and at least a portion of the plunger into the tap hole and axially displacing the sleeves relative to one another to displace the mortar radially outwardly of the plug to fill the gap between the plug and the walls of the tap hole, thereby sealing the tap hole with the mortar.
Accordingly, it is a primary object of the present invention to provide a novel and improved plug for the tap hole of a metallurgical vessel which may be readily and easily inserted into the tap hole and which plug carries mortar which can be displaced radially to seal against the walls of the tap hole.
It is another object of the present invention to provide novel and improved apparatus and methods for inserting the plug into the tap hole.
These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, appended drawings and claims.